The filling of pre-sterilized containers in an aseptic manner is known and various systems are employed which utilize different filling apparatus, different containers, and different sterilization techniques. Specifically, the container to be filled is produced in a manner which ensures that the interior of the container is sterilized during manufacture. During the filling procedure an inlet into the container is opened and a filling nozzle used to fill the container with a selected flowable material. The inlet is then sealed to thereby contain the flowable material within the container until dispensing is required. To ensure that the contents of the container is kept as free of contaminating bacteria and other micro organisms as possible it is essential that the act of filling the container does not in itself introduce contaminants into the interior of the container. Also, the resealing of the container after it is filled must be done in such a way that a proper seal is achieved so that contamination does not take place during transportation or storage.
Various prior art patents have addressed the aforementioned problems and reference may be made to U.S. Pat. No. 4,805,378 (Anderson), U.S. Pat. No. 2,930,170 (Holsman et al), U.S. Pat. No. 4,542,530 (Thomas et al) and U.S. Pat. No. 4,672,688 (Kalkipsakis). These prior art patents describe systems which are successful to a greater or lesser extent. However, the prior art systems do suffer from certain deficiencies, at least under some filling circumstances.
For example, U.S. Pat. No. 4,805,378 discloses an arrangement in which a flap is positioned across the mouth of the filling inlet, which provides some measure of obstruction to the flowable material entering the container. Current food processing plants can produce product at a rate of in excess of 20,000 liters per hour and it is important that the container is able to receive a product at this flow rate in order to avoid providing multiple head filling systems and the like. To achieve filling rates of this order relatively large diameter filling inlets are required into the containers and the flap system disclosed in U.S. Pat. No. 4,805,378, limits the diameter and flow rate into the container. Also, for highly viscous materials, and for materials which contain solid particles, the flap system is not always completely suitable.
The U.S. Pat. No. 4,805,378 discloses a container which is filled via an upstanding plastics collar, at one end of which a first flange is heat fused to the flexible plastic sheet wall of the container surrounding a filling opening in the container and, at a second flange at the opposite end of the collar, a rupturable sheet plastics membrane is also heat fused. The sheet plastics membrane, which is heat sterilized in manufacture but which most likely would be recontaminated externally before filling, is resterilized immediately prior to filling by a fluid (for example pressurized steam) after being brought into engagement with a filling head of an aseptic filler. In the described method, an incision tool forming part of the filling head, sterilized along with the exterior of the membrane, is advanced to cut the membrane then withdrawn to enable admission of the liquid to be packaged through the collar and through gaps formed between the flap partially heat fused to the flange inside the container.
As discussed in U.S. Pat. No. 4,805,378, the cutting of the resterilized membrane involves making a pair of straight incisions, crossed at right angles passing through the center of the membrane and extending radially outward to a point just inside the outer flange of the upstanding plastics collar. Accordingly, as the liquid or liquid-like product flows into the bag to fill it, the four cut tips or “reversed petals” of the membrane turn inwardly with the flow and extend towards the inner and end of the collar where it is connected to the bag in the region that is subsequently sealed closed as described. There are occasionally experienced instances of unreliability with this arrangement in that the four petals of the top membrane, since they remain on the filled sealed package, are difficult to clean underneath to remove remnants of the packaged product inside of the collar during the flushing cycle. Also, the petals tend to reduce the flow rate of the product into the container during filling which can be disadvantageous from a production point of view with viscous or particulate containing products.
There is furthermore a risk that the tips of the petals might wrap underneath the inside corner of the flange and be caught up in the subsequent final heat sealing operation. If this were to happen there would be a potential for a leakage path to bypass the seal or, at least, a potential source of failure of the seal. Accordingly, the axial height of the collar should be sufficient in relation to the diameter opening to prevent this possibility. In use commercially, the diameter of opening as disclosed in the Anderson patent is known to be in the range of 16–32 mm. With the desired future extension of the size of opening up to 60 mm or 70 mm, using the arrangement disclosed in the patent would require a corresponding increase in axial height of the collar. There would be no other need to increase the height of the collar other than to ensure that the cut petals of the membrane could not enter the sealing region, but such a high profile of collar would be unacceptable in general to fillers and end users of the package alike. It is therefore an object of this invention to provide a method which will overcome the disadvantages associated with a rupturable outer membrane.
Typically, the aforementioned packaging systems are used with high acid products, predominantly tomato paste, orange juice and juice concentrates. It is also known to use this type of packaging system with low acid products, such as milk, cream and egg pulp for example.
Manufacturers are beginning to take advantage of processing system developments and market acceptance, for an increased range of particulate and concentrate products. The types of products currently being considered for packaging are pineapple chunks, diced tomatoes, ready prepared meals, meat sauces, fruit particulate, and various other similar type products. These products come in a range of different acidities and larger diameter filling nozzles are generally required in order to fill containers at the required flow rate and accommodate larger particulate sizes.
Containers having capacity of 1,000 liters or more are typically used for bulk packaging and with increased capacity of processing plants there is currently a need for a high capacity, highly aseptic packaging system that utilizes a large diameter filling nozzle and provides a high quality seal after filling and which can be used with low acid products.